Image sensing devices made up of an array of laterally spaced sensors are well known and can take a variety of forms. The array can be viewed as being made up of a number of laterally offset regions, commonly referred to as pixels or sensing elements. The art has recognized that sensing advantages can be realized by forming a lens array having a convex lens or lenslets for each pixel.
A lenticular array placed in registration with the device serves to focus the incident light upon the photodiodes. One lenslet for each photodiode. This has the effect of increasing the light gathering area of each photodiode and hence improving the signal.
The device necessarily has to have a lens supporting structure. A color filter array may be provided on such structure. In any event, it is important that the structure have a planarized surface so that the lenses can be very accurately positioned.
A planarized surface is desirable in the manufacturing of lenslets for several reasons. By eliminating, or at least greatly reducing the topography, the ability of the photolithography processes to successfully pattern subsequent layers in the fabrication process is greatly enhanced.